Method of drilling wells



Patented May 15, 1923.

UNITED STATES PATENT CROSS REFERE 38E OFFICE.

JOHN C. SWAN, OF MARIETTA, OHIO.

METHOD or DRILLIITG WELLS.

No Drawing.

To all whom it may concern:

Be it known that I, JOHN C. SWAN, a citizen of the United States, residing at Marietta, in the county of Washington and State of Ohio, have invented certain new and useful Improvements in Methods of Drilling Wells, of which the following is a specification.

My invention relates to an lmprovement in the present methods of drilling wells, particularly wells drilled for oil. Heretofore, it has been the practice in the various stages of well drilling to use water either that naturally present in the well or added water for the purpose of making the action of the drilling tools operatively effective.

My invention consists broadly in the substitution for water, under certain conditions as hereinafter specified, of a viscid or viscous liquid preferably heavier than water and preferably also having additional qualities which furnish advantageous results in this particular art.

The liquid which I prefer to use is tar, and I prefer to use a neutral tar, or one free from alkaline. or acid ingredients. The tar, if not sufficiently liquid, may be brought to the desired liquid condition either by dilution of the mixture with suitable diluents or solvents such as the heavier oil fractions obtained in coal tar distillation; or with benzol or other solvent, or by heating it to make it more liquid.

My invention is capable of application under a number of the conditions arising in drilling wells. Thus, when starting a well, it is customary to drive pipe through the loose formation above hed-rock and water is added, if not naturally present.

The purpose of adding this water is to furnish a menstruum for the suspension of the drill grindings, in cleaning out the interior of the pipe or drilling below it. By substituting a heavier or viscid liquid for the water we get the advantage both of its greater fiotative capacity for suspending the sand and pebbles, and of its capacity to maintain these materials in suspension. When water is used the sand and pebbles must be ground to a fine powder under the action of the bit before obtaining this result.

Application filed October 2?, 1919. Serial No. 334,126.

In addition the viscid fluid infiltrates into the loose formations around the pipe and,

below the pipe after the drill bit has passed out of the lower end of the drive pipe, and will bind loose sand and gravels against so readily flowing into the hole drilled ahead of the pipe, thereby enabling the driller to push his operations further before the necessity arises for again driving pipe to greater depths, thus saving the time lost in making the necessary changes, to say nothing about the more rapid drilling accomplished below the pipe by the use of a viscid liquid.

Further, by the use of the drilling liquid, the exterior of the pipe is coated, the liquid acting as a lubricant to reduce the skin-- bed rock, it may be raised a short distance and a fresh supply of viscid liquid, which may be of such consistency as to become plastic or even congeal at the temperature of the water, is then fed into the pipe and displaced therefrom into the surrounding sand. When the pipe is again "lowered, the joint between the pipe and bed rock will be completely sealed. Obviously this method is applicable at any point in the well.

In shale formations, where they are known to have caving characteristics, a liquid of the kind described should be used exclusively for drilling, primarily for the purpose of filling and protecting the walls of the well as fast as the same are formed. For this particular drilling and wall-treating purpose combined, I recommend the use of very hot liquid, up to 400 F., as giving better results on the wall than colder or cold liquid, due to a better infiltration of the wall face by the heated liquid. When SEARCH ROM coal tar is used, owing to some not well understood reactions between coal tar and rock formations when the tar is applied at high temperatures, there is produced a hardening of the wall structure and practical protection against weathering and caving.

In rotary drilling it is customary to supply mud consisting of clay and water to the pumps which force the mud into proximity to the cuttin surfaces. This mud in returning outside of the drill pipes, in addition to removing the cuttings of the drill, plasters up the wall of the well and prevents caving, and tends to shut olf water and gas. In this type of drilling the substitution of a viscid liquid of the character above described for the mud heretofore used is particularly advantageous, since th removal of the cuttings takes place with greater facility and the viscid liquid is better adapted for sealing the wall of the well because of the permanent binding effect due to its viscidity. What has been here stated with reference to the rotary drilling is equally applicable to whatis now known as the cable tool hydraulic circulating system of drilling. In many instances where the use of the hydraulic circulating system has been considered essential, my method enables the use of the ordinary cable-tool process, because owing to the continuous treatment of the wall of the well by the viscid liquid, gas, water and caves are sealed off as fast as uncovered.

For the purpose of keeping the casin permanently loose and removable at will, the casing should be lowered into the well in such a manner as to force the viscid drilling fluid, as by pneumatic or hydraulic pressure, between the casing and the well wall for the entire length of the casing, thereby permanently shuttino' off all water from entering from behind tie easing into the well, thereby obviating the necessity of cementing the well, with all the expense, delays and disappointments incident to the use of that process. 7

The result of this operation is a cased well having on the exteribr of the casing a coating of viscid liquid in intimate contact with the wall of the well. This feature of my invention is applicable to wells which have been drilled by ordinary methods. In case it is desired to shut off from such wells any water or gas. the casing is raised a short distance. a sufficient quantity of the viscid liquid is lowered by a dump bailer. and the liquid is then displaced by any of the well-known methods and forced up around the outside of the casing. The casing is then lowered into its former position. he drilling liquid, such as tar, may be collected in sumps or tanks at the surface after having been used in the Well and can use of this fluid unless its added cost as compared with water proves it to be economical in the lessened wear of the steel of the bit and the time necessary for drilling a given distance; however, even in this type of drilling, the sand suspended in water has a constant tendency to settle out and stick the drilling tools unless they are kept in constant motion, and this action is prevented by the use of a heavy viscid liquid.

While I have specifically referred to coal tar as the drilling liquid which I use, other non-aqueous, non-hygroscopic liquids or solutions having like physical and chemical characteristics may be used, such as Wood tar, rosin dissolved in heavy tar oil, or asphalt dissolved in benzol.

While I prefer to use a liquid, such as coal tar, which is heavier than water, this characteristic is not in all cases essential as lighter liquids may in some instances be used.

A further very important advantage of my method is that the presence at the bottom of the well and around the casing, of a mobile but viscid liquid, particularly if such liquid be highly viscous or even plastic at the temperature there existing, so permanently seals the easing into the surrounding walls that blow-outs may be entirely obviated. The viscid liquid is conformable to any change in the conformation due to gas-pressure and therefore acts as an effective seal under all conditions.

I claim;

1. The method of drilling cased wells which consists in carrying out the drilling operations with an anti-corrosiveliquid more viscid than water, and having a higher specific gravity than water.

2. The method as claimed in claim lin which the viscid liquid is tar.

3. The -method of drilling cased wells .which consists in carrying out the drillin' operations with an anti-corrosive liqul more viscid than water and coating'the casing inside and out with the viscid liquid.

4. The method as claimed in claim 3 in which the wall of the well is impregnated with the viscid liquid.

The method of sealing cased wells which consists in displacing a viscid sealing fluid from within the easing into the sur rounding space, and then lowering the casing through the body of liquid.

6. The method of sealing cased wells which consists in introducing a non-aqueous non-hygroscopic viscid liquid 'into'the space between the casing and the surrounding wall of the well.

In testimony whereof I affix my si nature.

JOHN C. S Ah 

